A creepy Pokemon gets even creepier in Pokemon Sword and Shield. The new Pokemon games introduce several new "regional forms" of existing Pokemon, most of whom were changed due to living in the Galar region's unique habitats. While we first saw regional forms in Pokemon Sun and Moon, Pokemon Sword and Shield takes things one step further by introducing new Pokemon evolutions that can only be obtained by the regional variants of certain Pokemon.
One such Pokemon is Yamask, a Ghost-type Pokemon first introduced in Pokemon Black and White. Yamask was always a creepy Pokemon - the Pokemon is literally a spirit of a dead person that carries around a death mask of their face. However, in Pokemon Sword and Shield, the Pokemon carries around a stone fragment instead of its traditional mask. The reason is appropriately creepy - the stone contains cursed carvings and possessed Yamask, absorbing its dark power in the process.
The Galarian version of Yamask also has a new evolved form - Runerigus, which contains the full stone carving carried about by tendrils of dark energy. The Pokedex notes that the carving came to life after fully absorbing the Yamask. However, evolving Yamask into Runerigus requires a very specific method, one that doesn't involve leveling it up or exposing it to a specific item.
Players will need to bring their Yamask to the Dusty Bowl area of the Wild Area. Once there, players need to walk under the stone sculpture in the Dusty Bowl while it has at least 49 points of damage. This is probably the weirdest evolution method in Pokemon Sword and Shield yet, and this is a game that includes a Pokemon that requires your Switch to be upside down to evolve it.